Catheter with multiple electrode assemblies for use at or near tubular regions of the heart

ABSTRACT

A catheter with ablation and potential sensing capabilities is adapted for outer circumferential contact with an opening of a tubular region and inner circumferential contact within the tubular region. The catheter has a proximal electrode assembly and a distal electrode assembly for ablation of an ostium and potential sensing inside the pulmonary vein so that it is possible to obtain ECG signals inside a pulmonary vein when ablating around the ostium. The distal electrode assembly has an elongated member defining a longitudinal axis and a plurality of spines surrounding the member and converging at their proximal and distal ends, where each spine has at least one electrode and a curvature so that the spine bows radially outwardly from the member. The proximal electrode assembly has a proximal electrode assembly has an elongated member configured with a generally radial portion and a generally circular portion generally transverse to the catheter axis, where the generally circular portion comprising a plurality of electrodes. The control handle advantageously allows a user to manipulate a tensile member for changing the curvature of the spine.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/346,829, filed Dec. 30, 2008, the entire content of which isincorporated herein by reference.

FIELD OF INVENTION

This present invention relates to an improved electrophysiologiccatheter that is particularly useful for ablation and sensing electricalactivity at or near a tubular region of the heart.

BACKGROUND OF INVENTION

Cardiac arrythmias, and atrial fibrillation in particular, persist ascommon and dangerous medical ailments, especially in the agingpopulation. In patients with normal sinus rhythm, the heart, which iscomprised of atrial, ventricular, and excitatory conduction tissue, iselectrically excited to beat in a synchronous, patterned fashion. Inpatients with cardiac arrythmias, abnormal regions of cardiac tissue donot follow the synchronous beating cycle associated with normallyconductive tissue as in patients with normal sinus rhythm. Instead, theabnormal regions of cardiac tissue aberrantly conduct to adjacenttissue, thereby disrupting the cardiac cycle into an asynchronouscardiac rhythm. Such abnormal conduction has been previously known tooccur at various regions of the heart, such as, for example, in theregion of the sino-atrial (SA) node, along the conduction pathways ofthe atrioventricular (AV) node and the Bundle of His, or in the cardiacmuscle tissue forming the walls of the ventricular and atrial cardiacchambers.

Cardiac arrhythmias, including atrial arrhythmias, may be of amultiwavelet reentrant type, characterized by multiple asynchronousloops of electrical impulses that are scattered about the atrial chamberand are often self propagating. Alternatively, or in addition to themultiwavelet reenetrant type, cardiac arrhythmias may also have a focalorigin, such as when an isolated region of tissue in an atrium firesautonomously in a rapid, repetitive fashion.

A host of clinical conditions may result from the irregular cardiacfunction and resulting hemodynamic abnormalities associated with atrialfibrillation, including stroke, heart failure, and other thromboembolicevents. In fact, atrial fibrillation is believed to be a significantcause of cerebral stroke, wherein the abnormal hemodynamics in the leftatrium caused by the fibrillatory wall motion precipitate the formationof thrombus within the atrial chamber. A thromboembolism is ultimatelydislodged into the left ventricle, which thereafter pumps the embolisminto the cerebral circulation where a stroke results. Accordingly,numerous procedures for treating atrial arrhythmias have been developed,including pharmacological, surgical, and catheter ablation procedures.

It has been found that by mapping the electrical properties of theendocardium and the heart volume, and selectively ablating cardiactissue by application of energy, it is sometimes possible to cease ormodify the propagation of unwanted electrical signals from one portionof the heart to another. The ablation process destroys the unwantedelectrical pathways by formation of non-conducting lesions. Examples ofcatheter-based devices and treatment methods have generally targetedatrial segmentation with ablation catheter devices and methods adaptedto form linear or curvilinear lesions in the wall tissue which definesthe atrial chambers, such as those disclosed in U.S. Pat. No. 5,617,854to Munsif, U.S. Pat. No. 4,898,591 to Jang, et al., U.S. Pat. No.5,487,385 to Avitall, and U.S. Pat. No. 5,582,609 to Swanson, thedisclosures of which are incorporated herein by reference. In addition,various energy delivery modalities have been disclosed for forming suchatrial wall lesions, and include use of microwave, laser and morecommonly, radiofrequency energies to create conduction blocks along thecardiac tissue wall, as disclosed in WO 93/20767 to Stem, et al., U.S.Pat. No. 5,104,393 to Isner, et al. and U.S. Pat. No. 5,575,766 toSwartz, et al., respectively, the entire disclosures of which areincorporated herein by reference.

In this two-step procedure—mapping followed by ablation—electricalactivity at points in the heart is typically sensed and measured byadvancing a catheter containing one or more electrical sensors into theheart, and acquiring data at a multiplicity of points. These data arethen utilized to select the target areas at which ablation is to beperformed.

Mapping and ablation in regions of or near the pulmonary veins posesspecial challenges due to the configuration of the ostia and surroundingtubular tissue. Catheters have been developed that are particularlyuseful for mapping and ablating the pulmonary veins and other tubularregions of or near the heart, including the ostium. U.S. Pat. Nos.6,090,084 and 6,251,109 to Hassett et al., U.S. Pat. No. 6,117,101 toDiederich et al., U.S. Pat. No. 5,938,660 to Swartz et al., U.S. Pat.Nos. 6,245,064 and 6,024,740 to Lesh et al., U.S. Pat. Nos. 5,971,983,6,012,457 and 6,164,283 to Lesh, U.S. Pat. No. 6,004,269 to Crowley etal., and U.S. Pat. No. 6,064,902 to Haissaguerre et al., all of whichare incorporated herein by reference, describe apparatus for tissueablation to treat atrial arrhythmia, primarily tissue located within thepulmonary veins or on the ostia of the pulmonary veins. Catheters havinglasso, open-spine or closed-spine (basket) assemblies are also known.Such catheters are disclosed in, for example, U.S. Pat. Nos. 6,728,455,6,973,339, 7,003,342, 7,142,903, and 7,412,273, the entire disclosuresof which are hereby incorporated by reference.

“Lasso” catheters are particularly useful during circumferentialablations around the ostium of the pulmonary veins. One techniqueutilizes one catheter for mapping and finding abnormal potentials and asecond catheter for ablating the ostium. However, during a procedure itis desirable to have continuous feedback of the potential recordings orelectrograms (ECGs) inside the pulmonary vein (PV) as a circumferentialablation is performed around the vein's ostium. Having feedback of theECGs inside a pulmonary vein during PV ostium ablation allows a user toknow whether the undesired potentials have been successfully blocked bythe circumferential ablation. Currently, if the user desires real timeECG feedback from inside the pulmonary vein during a circumferentialablation, a third catheter is used. Accordingly, it is desired that asingle catheter be adapted to both ablate and detect potentials, and inparticular, that a single catheter have both a proximal electrodeassembly for ablating an ostium and a distal electrode assembly fordetecting potentials in the tubular region of the ablated ostium so thatit is possible to obtain ECG signals inside a pulmonary vein whenablating around the ostium.

SUMMARY OF THE INVENTION

The present invention is directed to a catheter with ablation andpotential sensing capabilities that is adapted for outer circumferentialcontact with an opening of a tubular region and inner circumferentialcontact within the tubular region. In one embodiment, the presentinvention provides a single catheter having both a proximal electrodeassembly and a distal electrode assembly for ablation of an ostium andpotential sensing inside the pulmonary vein so that it is possible toobtain ECG signals inside a pulmonary vein when ablating around theostium.

In a more detailed embodiment, the catheter has an elongated catheterbody and a control handle at its proximal end. At its distal end is anelectrode structure comprising a distal electrode assembly and aproximal electrode assembly. The distal electrode assembly has anelongated member defining a longitudinal axis and a plurality of spinessurrounding the member and converging at their proximal and distal ends,where each spine has at least one electrode and a curvature so that thespine bows radially outwardly from the member. The proximal electrodeassembly has a proximal electrode assembly has an elongated memberconfigured with a generally radial portion and a generally circularportion generally transverse to the catheter axis, where the generallycircular portion comprising a plurality of electrodes. The controlhandle advantageously allows a user to manipulate a tensile member forchanging the curvature of the spine. The catheter may also have adeflectable section between the catheter body and the electrodestructure where the control handle allows a user to manipulate a secondtensile member for deflecting the deflectable section.

In a more detailed embodiment, the catheter may have electrodes on thedistal electrode assembly that are adapted for sensing electricalactivity in the heart while having electrodes on the proximal electrodeassembly that are adapted for ablation. Moreover, the electrodeassemblies may have shape-memory elements to help the assemblies retaintheir shape.

In another embodiment, the catheter has a control handle has controlmembers that allow separate and independent control of tensile membersto deflect the intermediate section, to expand a basket electrodeassembly, and/or to contract a lasso electrode assembly. In a detailedembodiment, the control handle has a thumb control and a rotatable gripto draw different puller, deflection or contraction wires.

In a more detailed embodiment, the control handle has a handle body, acore and a piston that is longitudinally moveable relative to the coreand handle body. There are also a first anchor fixedly mounted to thecore, a cam receiver mounted within the handle body, a second anchorfixedly mounted to the cam receiver, and a cylindrical cam mounteddistal to the cam receiver in surrounding relation to the piston,wherein rotation of the cam relative to the piston causes longitudinalmovement of the cam receiver and second anchor.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 a is a top view of an embodiment of the catheter of the presentinvention.

FIG. 1 b is a perspective view of an embodiment of an electrodestructure of the present invention, including a proximal electrodeassembly and a distal electrode assembly, wherein the distal electrodeassembly is shown in a normal configuration (broken lines) and in anexpanded configuration (solid lines).

FIG. 2 is side elevational view of an embodiment of an electrodestructure positioned with a distal electrode assembly positioned in atubular region of the heart and a proximal electrode assembly on anostium of the tubular region.

FIG. 3 a is a side cross-sectional view of an embodiment of a catheterof the present invention, including a junction between a catheter bodyand an intermediate section along one diameter.

FIG. 3 b is a side cross-sectional view of an embodiment of a catheterof the present invention, including a junction between a catheter bodyand an intermediate section along another diameter.

FIG. 4 is an end cross-sectional view of an embodiment of anintermediate section of the catheter of the present invention.

FIG. 5 a is an end view of an embodiment of an electrode structure,including a proximal electrode assembly and a distal electrode assembly.

FIG. 5 b is a detailed view of an alternative embodiment of a portion ofan electrode structure, including a ring electrode, thermocouple wiresand a lead wire.

FIG. 6 a is a side cross-sectional view of an embodiment of a catheterof the present invention, including a junction of an intermediatesection and a connector tubing, taken along one diameter.

FIG. 6 b is a side cross-sectional view of an embodiment of a catheterof the present invention, including a junction of an intermediatesection and a connector tubing, taken along another diameter.

FIG. 6 c is an end cross-sectional view of a connector tubing of FIGS. 6a and 6 b, taken along line c-c.

FIG. 7 a is a side cross sectional view of an embodiment of a catheterof the present invention, including a proximal end of a distal electrodeassembly, taken along one diameter.

FIG. 7 b is a side cross sectional view of an embodiment of a catheterof the present invention, including a proximal end of a distal electrodeassembly, taken along another diameter.

FIG. 7 c is an end cross-sectional view of a proximal end of a distalelectrode assembly of FIGS. 7 a and 7 b taken along line c-c.

FIG. 8 a is a side cross sectional view of an embodiment a catheter ofthe present invention, including a distal end of a distal electrodeassembly, taken along one diameter.

FIG. 8 b is a side cross sectional view of an embodiment of a catheterof the present invention, including a distal end of a distal electrodeassembly, taken along another diameter.

FIG. 8 c is an end cross-sectional view of a distal end of a distalelectrode assembly of FIGS. 8 a and 8 b, taken along line c-c.

FIG. 8 d is an end cross-sectional view of a distal dome tip of FIGS. 8a and 8 b, taken along line d-d.

FIG. 9 is a side cross sectional view of an embodiment of a controlhandle of the present invention.

FIG. 10 is an exploded perspective view of interior components of thecontrol handle shown in FIG. 9.

FIG. 11 is an enlarged side cross-sectional view of the control handleof FIG. 9 showing a deflection wire adjuster and a contraction wireadjuster.

DETAILED DESCRIPTION OF THE INVENTION

In a disclosed embodiment of the invention, there is provided a catheter10 having an electrode structure 11 at its distal end. As shown in FIGS.1 a and 1 b, the catheter comprises an elongated catheter body 12 havingproximal and distal ends, an intermediate deflectable section 14 at thedistal end of the catheter body, and a control handle 16 at the proximalend of the catheter body. The electrode structure 11 extending from theintermediate section 14 has a proximal electrode assembly 15 and adistal electrode assembly 17. In the illustrated embodiment withreference to FIG. 2, the proximal electrode assembly 15 is lasso-shapedto sit on an opening 19 of a tubular region 21 of the heart, forexample, an ostium of a pulmonary vein, for circumferential tissuecontact at the opening. The distal electrode assembly 17 isbasket-shaped to extend past the opening 19 and into the tubular regionfor circumferential tissue contact with an inner surface 23 of thetubular region. In that regard, the distal electrode assembly 17 isexpandable to a greater diameter to ensure contact with the innersurface 23.

With reference to FIGS. 3 a and 3 b, the catheter body 12 comprises anelongated tubular construction having a single, axial or central lumen18. The catheter body 12 is flexible, i.e., bendable, but substantiallynon-compressible along its length. The catheter body 12 can be of anysuitable construction and made of any suitable material. A presentlypreferred construction comprises an outer wall 20 made of polyurethaneor PEBAX. The outer wall 20 comprises an embedded braided mesh ofstainless steel or the like to increase torsional stiffness of thecatheter body 12 so that, when the control handle 16 is rotated, theintermediate section 14 of the catheter 10 will rotate in acorresponding manner.

The outer diameter of the catheter body 12 is not critical, but ispreferably no more than about 8 french, more preferably 7 french.Likewise the thickness of the outer wall 20 is not critical, but is thinenough so that the central lumen 18 can accommodate puller wires, leadwires, and any other desired wires, cables or tubings. If desired, theinner surface of the outer wall 20 is lined with a stiffening tube 22 toprovide improved torsional stability. A disclosed embodiment, thecatheter has an outer wall 20 with an outer diameter of from about 0.090inch to about 0.94 inch and an inner diameter of from about 0.061 inchto about 0.065 inch.

With additional reference to FIG. 4 a, the intermediate section 14comprises a short section of tubing 13 having multiple lumens, forexample three to five lumens. In the disclosed embodiment, there arelumens 24, 25, 26 and 27. The first lumen 24 carries lead wires 30 forring electrodes of the lasso electrode assembly 15, lead wires 32 forring electrodes of the basket electrode assembly 17, and thermocouplewires 41 and 45 for measuring temperature, for example, at the ringelectrode(s), where the catheter is constructed for bipolar ablation.The second lumen 25 carries a first tensile member or deflection wire 34for deflecting the intermediate section 14. The third lumen 26 carries acable 36 for an electromagnetic location sensor 33 located at or nearthe electrode structure 11. The fourth lumen 27 carries a tubing 40having a lumen 67 suitable for a guidewire to pass, and through which asecond tensile member or puller wire 47 extends for expanding the basketelectrode assembly 17.

The tubing 13 of the intermediate section 14 is made of a suitablenon-toxic material that is preferably more flexible than the catheterbody 12. A suitable material for the tubing 13 is braided PEBAX orpolyurethane, i.e., polyurethane with an embedded mesh of braidedstainless steel or the like. The size of each lumen is not critical, butis sufficient to house the respective components extending therethrough.

The useful length of the catheter, i.e., that portion that can beinserted into the body excluding the assemblies 15 and 17, can vary asdesired. In one embodiment, the useful length ranges from about 110 cmto about 120 cm. The length of the intermediate section 14 is arelatively small portion of the useful length, and preferably rangesfrom about 3.5 cm to about 10 cm, more preferably about 4 cm to about 8cm, and still more preferably about 6.5 cm.

A means for attaching the catheter body 12 to the intermediate section14 is illustrated in FIGS. 3 a and 3 b. The proximal end of theintermediate section 14 comprises an outer circumferential notch 31 thatreceives the inner surface of the outer wall 20 of the catheter body 12.The intermediate section 14 and catheter body 12 are attached by glue orthe like.

If desired, a spacer (not shown) can be located within the catheter bodybetween the distal end of the stiffening tube (if provided) and theproximal end of the intermediate section. The spacer provides atransition in flexibility at the junction of the catheter body andintermediate section, which allows this junction to bend smoothlywithout folding or kinking. A catheter having such a spacer is describedin U.S. Pat. No. 5,964,757, the disclosure of which is incorporatedherein by reference.

At the distal end of the intermediate section 14 is the electrodestructure 11 having a proximal assembly 15 adapted to sit on an openingof a tubular region, and a distal assembly 17 adapted to enter thetubular region and contact the inner surface of the tubular region (FIG.2). The assemblies 15 and 17 are generally concentric about the axis ofthe deflectable intermediate section 14. With reference to FIGS. 1 b and5 a, the proximal assembly 15 comprises a connecting segment 38 and agenerally circular main segment 39. The segment 38 is generally straightand extending radially from the distal end of the intermediate section14. The length of the segment 38 is about equal to the radius of thegenerally circular main segment 39 such that the generally circular mainsegment is generally concentric with the distal end of the intermediatesection 14. The proximal assembly 15 has an exposed length, e.g., notcontained within the intermediate section 14, ranging between about 20mm and about 70 mm, more preferably about 25 mm and about 50 mm, stillmore preferably about 42 mm, but can vary as desired.

The generally circular main segment 39 is generally traverse to thecatheter body 12 and is preferably generally perpendicular to thecatheter body 12. The generally circular main segment 39 need not form aflat circle, but can be very slightly helical. The main segment 39 hasan exposed length ranging between about 40 mm and 100 mm, morepreferably about 50 mm and 90 mm, and still more preferably about 60 mm,and an outer diameter preferably ranging to about 10 mm to about 35 mm,more preferably about 15 mm to about 30 mm, still more preferably about25 mm. The main segment 39 can curve in a clockwise direction, as shownin FIG. 6 or a counterclockwise direction, as shown in FIG. 1 b.

The proximal assembly 15 comprises a non-conductive covering or tubing50 (shown partially broken away in FIG. 5 a) that spans the length ofthe segments 38 and 39. The covering or tubing 50 can be made of anysuitable material that is flexible and biocompatible and preferablyplastic, such as polyurethane or PEBAX. The tubing 50 (as with all tubesor tubing herein) may have any cross-sectional shape and may have asingle lumen or multiple lumens. The illustrated embodiment, the tubing50 has a single lumen that is occupied by lead wires 30 or otherelectrical connections for ring electrodes 52 or any other electrical orelectromagnetic elements that may be mounted on the proximal assembly15. Moreover, the lumen is occupied by a support element 53 that canhave shape memory or be preformed with the radial and generally circularshape. A shape memory element can be straightened or bent out of itsoriginal shape upon exertion of a force and is capable of substantiallyreturning to its original shape upon removal of the force. A suitablematerial for the shape memory element is a nickel/titanium alloy. Suchalloys typically comprise about 55% nickel and 45% titanium, but maycomprise from about 54% to about 57% nickel with the balance beingtitanium. A preferred nickel/titanium alloy is nitinol, which hasexcellent shape memory, together with ductility, strength, corrosionresistance, electrical resistivity and temperature stability.

A means for attaching the tubing 50 of the proximal electrode assembly15 to the catheter is illustrated in FIGS. 4 b and 6 a. A nonconductiveconnector tubing 57 constructed of a biocompatible materials, e.g.,PEEK, with a single lumen, extends from the distal end of the tubing 13of the intermediate section 14. An opening 58 is cut or otherwise formedin the wall of the tubing 57 to receive a proximal end of the tubing 50which can extend proximally into the lumen 24 of the tubing 13 and beaffixed by glue 60 which also seals the opening 58. The lead wires 30for the proximal assembly 15 extend from the lumen 24 of the tubing 13of the intermediate section 14, and into the tubing 50 where they passthrough the radial segment 38 and the generally circular main segment 39of the proximal assembly 15. On the generally circular main segment 39are mounted multiple ring electrodes 52, each connected to a respectivelead wire 30 as shown in FIGS. 5 a and 5 b. The support member 53 alsoextends through the length of the tubing 50 to give shape and support tothe segments 38 and 39 of the proximal assembly 15. A proximal end ofthe member 53 is anchored in the lumen 24 of the intermediate section 14(FIG. 6 a).

As shown in FIG. 5 a, the distal end of the proximal assembly 15 issealed with a dome 54 of polyurethane glue or the like. A short ring 56,made of metal or plastic, and preferably polyamide, is mounted withinthe distal end of the non-conductive cover 50. The short ring 56prevents the distal end of the non-conductive cover 50 from collapsing,there by maintaining the diameter of the non-conductive cover at itsdistal end.

As shown in FIGS. 6 a-6 c, the electromagnetic position sensor 33 ishoused in the nonconductive connector tubing 57 as other components passdistally through the tubing 57, including the tubing 40 containing thepuller wire 47 for the distal electrode assembly 17 (both from the lumen27 of the tubing 13), the lead wires 32 (from the lumen 24) for ringelectrodes 64 mounted on the distal assembly 17. The cable 36 for thesensor 33 passes through the lumen 26 of the intermediate section 14.

Distal the proximal electrode assembly 15 is the distal electrodeassembly 17. As shown in FIGS. 1 b, 7 a-7 c, the basket-shaped electrodeassembly 17 extends between two fasteners, for example, nitinol rings 65and 66, that define the proximal and distal ends of the assembly 17. Thedistal assembly 17 comprises a plurality of spines or arms 70 mounted,preferably generally evenly-spaced, around the tubing 40 which definesthe longitudinal axis of the distal assembly 17. The spines have aconvex curvature where each spine bows radially outwardly from thetubing 40, such that the spines converge at their distal and proximalends at the rings 65 and 66.

With reference to FIG. 5 a, each spine 70 of the basket assembly 17comprises a flexible wire 72 (with or without shape memory) with anon-conductive covering or tubing 71 on which one or more ringelectrodes 64 are mounted. In a preferred embodiment, the flexible wires72 each comprise a flat Nitinol wire and the non-conductive tubing 71each comprise a biocompatible plastic, such as polyurethane or PEBAX.The length of the tubings 71 is shorter than the length of the wires sothat there are exposed proximal and distal ends of the wires not coveredby the tubings. Alternatively, the spines 70 can be designed without theinternal flexible wire if a sufficiently rigid non-conductive materialis used for the non-conductive covering to permit expansion of theelectrode assembly, so long as the spine has an outer surface that isnon-conductive over at least a part of its surface for mounting of thering electrodes 64. As will be recognized by one skilled in the art, thenumber of spines 70 can vary as desired depending on the particularapplication, so that the assembly has at least two spines, preferably atleast three spines, and as many as eight or more spines. The term“basket-shaped” as used herein in describing the electrode assembly 17is not limited to the depicted configuration, but can include otherdesigns, such as spherical or egg-shaped designs, that include aplurality of expandable arms connected, directly or indirectly, at theirproximal and distal ends.

An embodiment of the distal end of the electrode assembly 17 is depictedin FIGS. 8 a 8 c. The distal end of a distal ring 66 is sealed by abiocompatible material, such as polyurethane, which is formed into anatraumatic dome 95. The exposed distal ends of the support members 72 ofthe spines 70 extending pass the coverings 71 are affixed, e.g., bysoldering 99, preferably evenly-spaced, to an inner surface 97 of thering 66. This junction between the spines 70, the tubing 40 and theproximal end of the ring 66 is sealed by a biocompatible material 93,such as polyurethane.

An embodiment of the proximal end of the electrode assembly 17 has asimilar construction, as shown in FIGS. 7 a-7 c, where the exposedproximal ends of the support members 72 are affixed to an inner surface97 of the ring 65, e.g., by soldering 99 or glue, and the junctionbetween the spines 70, the tubing 40 and the distal end of the ring 65is sealed by a biocompatible material 93. The rings 65 and 66 can bemade of metal or plastic, so long as it is sufficient rigid to achievethe above-stated function. It is understood that the spines can beformed from a unitary structure, such as a cylinder or tube that islaser cut with longitudinal cuts extending between its two opposing endsto form the spines. As would be recognized by one skilled in the art,other arrangements for attaching and arranging the spines and tubing 40could also be used in accordance with the invention.

The tubing 40 is generally coaxial with the intermediate section 14. Thetubing 40 has a distal end distal the distal ring 66 and a proximal endthat is in the control handle 16 such that its lumen 67 provides apathway for the second puller wire 47 between the control handle 16 andthe distal assembly 17, as well as a pathway for a guidewire to extendthrough the entire length of the catheter for introduction of thecatheter into a patient's body. Accordingly, the tubing 40 extendsproximally through the rings 66 and 65, the connector tubing 57, thelumen 27 of the intermediate section 14, the central lumen of thecatheter body 12, and the control handle 16.

The puller wire 47 for expanding the distal basket assembly 17 can madeof any suitable metal, such as stainless steel or Nitinol, and ispreferably coated with Teflon® or the like. The coating impartslubricity to the puller wire. The puller wire preferably has a diameterranging from about 0.006 to about 0.010 inch. The puller wire 47 isanchored at its proximal end in the control handle 16 and extendsdistally through the central lumen 18 of the catheter shaft 12 and thefourth lumen 27 of the intermediate section 14.

The distal end of the puller wire 47 is anchored in a distal tip 80 atthe distal ring 66 by means of a T-shaped anchor 81 with a shortstainless steel tubing crimped onto the puller wire 47, and a weldedcross-piece 82 that is distal of the distal ring 66 and extends thewidth of the ring 66. So anchored against the ring 66, the puller wire47 can be manipulated via the control handle 16 as described furtherbelow, thereby changing the curvature of the spines 70. In particular,as the puller wire is drawn proximally, the tubing 40 between the rings65 and 65 is compressed thereby decreasing the separation between therings 65 and 66, thus expanding (widening) the basket assembly 17 as thespines 70 bow further outwardly under the compression force applied bythe puller wire 47. As shown in FIG. 1 b, the basket-shaped assembly 17can be varied between (and to adopt either of) a more elongated orresting configuration with a smaller diameter (broken lines) and anexpanded configuration with a greater diameter (solid lines). Thelargest diameter at a mid-section of the basket assembly 17 can rangebetween about 10 mm and 30 mm, and preferably between about 15 mm and 25mm.

Each of the ring electrodes 52 and 64 of the electrode assemblies 15 and17 is electrically connected to an appropriate mapping or monitoringsystem and/or source of ablation energy by means of respective electrodelead wires 30 and 32. Each electrode lead wire has its proximal endterminating in a connector 111 (FIG. 1) at the proximal end of thecontrol handle 16. Distally, the electrode lead wires extend through thecontrol handle 16, the central lumen 18 in the catheter body 12, andthrough the lumen 24 of the intermediate section 14. The portion of thelead wires 30 and 32 extending through the central lumen 18 of thecatheter body 12, control handle 16 and proximal end of the lumen 24 areenclosed within a protective sheath (not shown), which can be made ofany suitable material, preferably polyimide. The protective sheath canbe anchored at its distal end to the proximal end of the intermediatesection 14 by gluing it in the lumen 24 with polyurethane glue or thelike.

Near the distal end of the intermediate section 14, the lead wires 30for the lasso electrode assembly 15 and the lead wires 32 for the basketelectrode assembly 17 diverge with the lead wires 30 entering the tubing50 of the electrode assembly 15. The lead wires 32 for the basketelectrode assembly 17 however extend out of the lumen 24, through theconnector tubing 57, through the proximal ring 65 and through theirrespective covering 71 of the spines 71 of the assembly 17. Each leadwire is attached to its corresponding ring electrode by any suitablemethod.

A preferred method for attaching a lead wire to a ring electrodeinvolves first making a small hole through the wall of thenon-conductive covering. Such a hole can be created, for example, byinserting a needle through the non-conductive covering and heating theneedle sufficiently to form a permanent hole. The lead wire is thendrawn through the hole by using a microhook or the like. The end of thelead wire is then stripped of any coating and welded to the underside ofthe ring electrode, which is then slid into position over the hole andfixed in place with polyurethane glue 91 or the like (FIG. 5 b).Alternatively, each ring electrode is formed by wrapping a lead wirearound the non-conductive covering a number of times and stripping thelead wire of its own insulated coating on its outwardly facing surfaces.

The ring electrodes can be made of any suitable solid conductivematerial, such as platinum or gold, preferably a combination of platinumand iridium, and mounted onto the tubing with glue or the like.Alternatively, the ring electrodes can be formed by coating the tubingwith an electrically conducting material, like platinum, gold and/oriridium. The coating can be applied using sputtering, ion beamdeposition or an equivalent technique. While unipolar ring electrodesare illustrated herein, it is understood that bi-polar ring electrodesmay be used.

The number of the ring electrodes on the assemblies can vary as desired.Preferably, the number of ring electrodes on the lasso assembly 15ranges from about six to about twenty, preferably from about eight toabout twelve, evenly spaced from each other. For the basket assembly 17,the number of ring electrodes on each spine ranges from about one toabout four, preferably about three that are more concentrated in theoutermost region of each spine. In a disclosed embodiment, a distance ofapproximately 5 mm is provided between each ring electrodes on the lassoassembly 15 and a distance of approximately 2 mm is provided betweeneach ring electrode on each spine of the basket assembly.

Where any of the ring electrodes of the assemblies 15 and 17 are adaptedfor ablation, a pair of thermocouple wires can be provided to detecttemperature of a respective ring electrode. In the disclosed embodiment,one pair of thermocouple wires 41 and 45 are provided, for example, forone of the ring electrodes of the proximal electrode assembly 15. Thethermocouple wires 41 and 45 extend through the central lumen 18 of thecatheter body 12 (FIG. 3A), through the lumen 26 of the tubing 13 of theintermediate section 14 (FIG. 4 a), and through the tubing 50 of theproximal electrode assembly 15, where their distal ends are positionednear the ring electrode to sense temperature (FIG. 6 a).

The deflection wire 34 for deflection of the intermediate shaft 14 hasmany similarities to the basket assembly puller wire 47 as describedabove. Some of the differences are described below.

The deflection wire 34 is anchored at its proximal end in the controlhandle 16 and extends distally through the central lumen 18 of thecatheter shaft 12 and the second lumen 25 of the intermediate section 14(FIG. 4 a) where its distal end is anchored to the distal end of theintermediate section 14, as shown in FIG. 6 b. Specifically, a T-shapedanchor is formed, which comprises a short piece of tubular stainlesssteel 43, e.g., hypodermic stock, which is fitted over the distal end ofthe deflection wire crimped to fixedly secure it to the puller wire. Thedistal end of the tubular stainless steel 43 is fixedly attached, e.g.,by welding, to a cross-piece 44 formed of stainless steel ribbon or thelike. The cross-piece 44 extends through a hole 46 formed in the tubing13 and because the cross-piece 44 is larger than the hole 46 and,therefore, cannot be pulled through the hole, the cross-piece 44 anchorsthe distal end of the deflection wire 34 to the distal end of theintermediate section 14.

A compression coil 35 is situated within the catheter body 12 insurrounding relation to the deflection wire 34. In the disclosedembodiment, the compression coil 35 extends from the proximal end of thecatheter body 12 to the proximal end of the intermediate section 14 (seeFIG. 3 b). The compression coil 35 is made of any suitable metal,preferably stainless steel, and is tightly wound on itself to provideflexibility, i.e., bending, but to resist compression. The innerdiameter of the compression coil is preferably slightly larger than thediameter of the deflection wire 34. The Teflon® coating on thedeflection wire 34 allows it to slide freely within the compressioncoil. Within the catheter body 12, the outer surface of the compressioncoil 35 is also covered by a flexible, non-conductive sheath 68, e.g.,made of polyimide tubing. The compression coil is anchored at itsproximal end to the outer wall 20 of the catheter body 12 by a proximalglue joint and to the intermediate shaft 14 by a distal glue joint.Within the lumen 25 of the intermediate shaft 14, the deflection wire 34extends through a plastic, preferably Teflon®, puller wire sheath 37,which prevents the deflection wire 34 from cutting into the wall of thetubing 13 when the intermediate section 14 is deflected.

A compression coil 103 is also provided for the puller wire 47 extendingthrough the tubing 40. In the disclosed embodiment, the distal end ofthe coil 103 is in the connector tubing 57, a few millimeters distal ofthe location of the opening 58. The proximal end of the compression coil103 is at or near the proximal end of the catheter body 12. A tubing 101surrounds the puller wire 47 within the compression coil 103. The tubing101 may be a tight fitting tubing of TEFLON.

Separate and independent longitudinal movement of the deflection wire 34and the puller wire 47 relative to the catheter body 12, which resultsin, respectively, deflection of the intermediate section 14 andexpansion of the distal electrode assembly 17, is accomplished bysuitable manipulation of the control handle 16. A suitable controlhandle is disclosed in U.S. Pat. No. 6,987,995 to Drysen entitledMultifunctional Catheter Handle, the entire disclosure of which ishereby incorporated by reference. As shown in FIGS. 1 and 9, the controlhandle 16 has a thumb control knob 184, and a cam 120 rotatable by meansof a flexible grip 128 that can be independently manipulated by a user.

In the embodiment of FIGS. 9 to 11, the control handle 16 includes ahandle body 174 in which a core 176 is fixedly mounted. Although in thedepicted embodiment, the core 176 is separate from the handle body 174,the core could instead be formed as a single unitary piece with thehandle body. The core has a generally cylindrical distal region 175 anda generally cylindrical proximal region 177 having a larger diameterthan the distal region. For longitudinal movement of the deflection wire34, a piston 182 is slidably mounted over the distal region 177 of thecore 176. The proximal end of the piston 182 is maintained within thehandle body 174, and the distal end of the piston extends outside thehandle body. The thumb knob 184 is mounted in surrounding relation to aportion of the distal end of the piston 182 so that the user can moreeasily move the piston longitudinally relative to the core 176 andhandle body 174. The proximal end of the catheter body 12 is fixedlymounted to the distal end of the piston 182 through a tip portion 178that is mounted on the distal end of the piston. The proximal end of thecatheter body 12 is inserted into an axial passage 180 in the tipportion and optionally glued in place. The piston includes an axialpassage 186 in communication with the axial passage 180 of the tipportion 178, and the core 176 includes an axial passage 188 incommunication with the axial passage in the piston.

The lead wires 30 and 32 (not shown for better clarity of othercomponents in the control handle), the puller wire 47 and deflectionwire 34 that extend through the catheter body 12 extend out the proximalend of the catheter body and through the axial passages in the tipportion 178, piston 182 and core 176. The lead wires can extend out theproximal end of the control handle 16 or can be connected to a connector(not shown) that is incorporated into the control handle, as isgenerally known in the art.

The proximal end of the deflection wire 34 is anchored to the core 176.As best seen in FIG. 11, the portion of the axial passage 188 extendingthrough the proximal region 177 of the core 176 has a larger diameterthan the portion of the axial passage extending through the distalregion 175 of the core 176. A deflection wire adjuster 190 is adjustablymounted, as described further below, in a portion of the axial passage188 near the distal end of the proximal region 177 of the core 176. Thedeflection wire adjuster 190 has an opening 192 extending therethroughin a direction generally transverse, and preferably generallyperpendicular, to the axial passage 188 of the core 176. The deflectionwire 34 extends through the opening 192 in the deflection wire adjuster190 such that the deflection wire changes directions.

The distal region 177 of the core 176 includes a generally rectangularopening 194 that extends generally parallel to the axial passage 188 ofthe core. A channel 196 connects the proximal end of the generallyrectangular opening 194 to the distal end of the portion of the axialpassage 188 in the proximal region 175 of the core 176. The proximal endof the deflection wire 164 extends through the channel 196 and into thegenerally rectangular opening 194. A deflection wire anchor 198, whichcan comprise a short piece of hypodermic stock, is fixedly attached, forexample, by crimping, to a portion of the proximal end of the deflectionwire 164 within the generally rectangular opening 194. The deflectionwire anchor 198 has a diameter greater than the width of the channel 196and thus prevents the proximal end of the deflection wire 34 from beingpulled through the channel, thereby anchoring the deflection wire to thecore 176. Thus, the deflection wire anchor 198 is fixedly mounted to thecore 176 even though the deflection wire anchor still has a small amountof free play within the opening 194.

In use, the piston 182 is moved distally relative to the handle body 74and core 176 by means of the thumb knob 184, thereby pulling thecatheter body 12 distally relative to the deflection wire 34, which isanchored to the core. As a result, the deflection wire 34 pulls on theside of the intermediate shaft 14 to which it is anchored, therebydeflecting the distal shaft in that direction. To straighten theintermediate shaft 14, the piston 182 is moved proximally back to itsoriginal position relative to the handle body 174 and core 176.

Manipulation of the deflection wire adjuster 190 adjusts the amount offree play in the deflection wire 34. As noted above, the deflection wireadjuster 190 is adjustably mounted in a portion of the axial passage 188near the distal end of the proximal region 177 of the core 176. Theportion of the axial passage 88 in which the deflection wire adjuster190 is mounted includes a series of ridges 100 extending along thesurface of the core 176, with the ridges being generally perpendicularto the axis of the core. The deflection wire adjuster 190 carries anoutwardly extending tab 102 that fits in the spaces between the ridges100. The deflection wire adjuster 190 can be moved along the length ofthe core 176 and snapped into place by placing the tab 102 between tworidges 100. As the deflection wire adjuster 190 is moved proximally(away from catheter body 12) less free play is provided for thedeflection wire 34. The precise mechanism for adjusting the amount offree play of the deflection wire 34 is not critical, and alternativemechanisms can be provided. Alternatively, the deflection wire 34 can beanchored directly to the core 176 so that it is not adjustable.

The control handle 16 is also used for longitudinal movement of thepuller wire 47 for expanding the basket assembly 17 by means of theflexible grip 128. The puller wire 47 extends from the catheter body 12,through the axial passage 186 in the piston 182 and through the axialpassage 188 within the distal region 175 of the core 176. The proximalend of the puller wire 47 is anchored to a contraction wire adjuster 104that is slidably mounted in the core 176.

The puller wire adjuster 104 is generally rectangular having a bottomregion 108 that extends downward through a slot 110 in the proximalregion 177 of the core 176, the slot being in communication with theaxial passage 188 of the core. The proximal end of the puller wire 47,which, as noted above, extends through the axial passage 188, isanchored in the puller wire adjuster 104 in a manner very similar to themanner in which the deflection wire 164 is anchored to the core 176, asdescribed above. Specifically, a puller wire anchor 108, which cancomprise a short piece of hypodermic stock, is fixedly attached, forexample, by crimping, to a portion of the proximal end of the pullerwire 47 within an opening 110 in the puller wire adjuster 104. A channel112 connects the opening 110 to the axial passage 88 in the core. Thepuller wire anchor 98 has a diameter greater than the width of thechannel 112 and thus prevents the proximal end of the puller wire 47from being pulled through the channel, thereby anchoring the puller wireto the puller wire adjuster 104. The distal end of the puller wireadjuster 104 is adjustably attached to a cam receiver 106. The camreceiver 106 is generally tubular, having a short slot 114 extendingfrom its proximal end sized to receive the distal end of the puller wireadjuster 104. The cam receiver 106 is slidably mounted over the piston182 and the distal region 175 of the core 176 with the bottom portion ofthe puller wire adjuster 104 positioned in the slot 114 in the core anda corresponding slot 115 in the piston. Thus, the puller wire anchor 98is fixedly mounted to the cam receiver 106 through the puller wireadjuster 104, even though the puller wire anchor has some free playwithin the opening 110 in the puller wire adjuster.

As shown in FIG. 10, the top of the distal end of the puller wireadjuster 104 includes a series of outwardly extending teeth 116 thatmate with a plurality of notches 118 within the slot 114 of the camreceiver 106 so that the puller wire adjuster can be snapped into thecam receiver. The position of the puller wire adjuster 104 relative tothe cam receiver 106 can be longitudinally adjusted by repositioning theteeth 116 relative to the notches 118, to thereby adjust the tension onthe puller wire 47. Alternatively, the puller wire 40 is not adjustable,in which case the puller wire anchor 98 is mounted within an opening(not shown) within the cam receiver 106.

Longitudinal movement of the cam receiver 106 and puller wire adjuster104 relative to the core 76, to which the catheter body 12 is indirectlymounted, results in longitudinal movement of the puller wire 47 relativeto the catheter body. Longitudinal movement of the cam receiver 106 isaccomplished through a cam 120 mounted in the control handle 16 insurrounding relation to the piston 182 and distal region 175 of the core176. A retaining ring 121 maintains the longitudinal position of the cam120 relative to the handle body 74.

The cam 120 includes a ramped proximal surface 122. The cam receiver 106includes a ramped distal surface 123 and an outwardly extending tab 124at the most distal point of the ramped distal surface. The tab 124contacts the ramped proximal surface 122 of the cam 120. When the cam120 is rotated counterclockwise, the ramped proximal surface 112correspondingly rotates and pushes the cam receiver 104 proximallyrelative to the core 176 and catheter body 12. As the cam receiver 104and the attached puller wire adjuster 104 are moved proximally relativeto the core 176 and catheter body 12, the puller wire 47 is pulledproximally to thereby expand the basket assembly 17.

The ramped proximal surface 122 of the cam 120 includes an outwardlyextending tab 126 at its most proximal point. As the cam 120 is rotatedcounterclockwise, the tab 124 on the cam receiver 104 contacts the tab126 on the ramped proximal surface 122, thereby prohibiting furtherrotation of the cam relative to the cam receiver. As the cam 120 isrotated clockwise, the tab 126 on the ramped proximal surface 122 pushesthe tab 124 on the cam receiver 104 such that the cam receiver movesdistally, thereby releasing the tension on the puller wire 47 so thatthe basket assembly 17 returns to its original configuration. As wouldbe recognized by one skilled in the art, the direction of the rampedproximal surface 122 can be changed so that clockwise rotation of thecam 120 causes expansion of the basket assembly and counterclockwiserotation causes it to return to its original configuration. The flexiblegrip 128 is provided over the cam 120 for the user to more easily andcomfortably rotate the cam 120.

In use, a suitable guiding sheath is inserted into the patient with itsdistal end positioned at a desired tubular region of the heart such as apulmonary vein. An example of a suitable guiding sheath for use inconnection with the present invention is the Preface™ Braiding GuidingSheath, commercially available from Biosense Webster, Inc. (Diamond Bar,Calif.). The distal end of the sheath is guided toward the ostium of thepulmonary vein and a catheter of the present invention is fed throughthe guiding sheath until its distal and proximal electrode assemblies 15and 17 both extend out of the distal end of the guiding sheath. As thecatheter is fed through the guiding sheath, the spines of the basketassembly 17 are pressed inwardly toward the tubing 40 so that theassembly 17 adopts a more elongated profile, and the lasso assembly 15is straightened with the distal dome end 54 leading through the sheath.Once the distal tip 80 of the catheter is positioned at the desiredtreatment location, the guiding sheath is pulled proximally, exposingthe deflectable intermediate section 14 and the assemblies 15 and 17 toextend outside the sheath, whereupon the assemblies return to theiroriginal shapes due to the shape-memory of the support members 53 and72. The user can manipulate the thumb control 184 of the control handle16 to deflect the intermediate section 14 for positioning the assemblies15 and 17 as appropriate. With proper manipulation, the basket assembly17 is inserted into a pulmonary vein or other tubular region (such asthe coronary sinus, superior vena cava, or inferior vena cava) so thatthe lasso assembly 15 comes into contact and sits on the ostium and theelectrodes 52 are positioned circumferentially about the ostium.Manipulation of the flexible grip 128 of the control handle 16 expandsthe basket assembly 17 within the tubular region so that the electrodes64 come into contact with a circumferential inner surface of the tubularregion. The user may then apply energy (e.g., RF, laser, or microwave)to the electrodes 52 of the lasso assembly 15 to form a generallycircumferential lesion ring around the ostium, especially by rotatingthe catheter handle 16 and the catheter body 12 which rotationtranslates along the length of the catheter to the electrode assemblies15 and 17. The electrodes 64 of the basket assembly 17 are in contactwith a circumference inside the tubular region. Preferably at leastabout 50%, more preferably at least about 70%, and still more preferablyat least about 80% of the circumference of the generally circular mainregion is in contact with a circumference inside the tubular region. Thecircular arrangement of the electrodes 64 of the distal basket assembly15 permits measurement of the electrical activity at that circumferenceof the tubular structure so that the catheter can provide real-time andcontinuous feedback of the potential recordings or electrograms (ECGs)inside the tubular region as a circumferential ablation is performedaround the vein's ostium by the proximal lasso assembly 15.

In an alternative embodiment, the deflection wire 34 is replaced by oradapted to function as a contraction wire to contract the generallycircular main region 39 to thereby reduce its diameter. The foregoingdescription of the deflection wire as to its configuration in thecontrol handle 16, the catheter shaft 12 and the intermediate section 14applies to this alternative embodiment, except for differences thatinclude the extension of the wire through the tubing 50 of the lassoassembly 15 and its distal end being anchored in the distal tip 54.Contraction of the lasso assembly could still be accomplished bymanipulation of the thumb control knob 184 as described above.

As understood by one of ordinary skill in the art, the tubing 50 may beadapted, such as a plastic tube of multiple layering, including an innerlayer of polyimide over which a braided layer is formed, the braidedlayer comprising a braided stainless steel mesh or the like, as isgenerally known in the art, for reducing the tendency for contractionwire to straighten the preformed curve of the lasso assembly 15. A thinplastic layer of polytetrafluoroethylene is provided over the braidedlayer to protect the braided layer from getting tangled with the leadwires within the non-conductive cover. The plastic tube has a proximalend anchored to the distal end of the intermediate section 14. Thesupport member 53 extends through the plastic tube with the contractionwire. The distal end of the support member 53 and the contraction wireare soldered or otherwise attached to a small stainless steel tube 44.With this arrangement, the relative positions of the contraction wireand the support member 53 can be controlled so that the contraction wirecan be positioned on the side of the generally circular region closer tothe center of the generally circular region, as described above. Thecontraction wire on the inside of the curve pulls the support member 53to the inside of the curve, enhancing contraction of the generallycircular region 39. Further, when the plastic tube 42 includes a braidedlayer, it keeps the contraction wire from tearing through thenon-conductive cover.

It is understood by one of ordinary skill in the art that the catheterof the present invention can be readily adapted so that either thumbcontrol or the flexible grip of the control handle 16 can deflect theintermediate section 14, contract the lasso assembly 15 or expand thebasket assembly 17 by means of a tensile member, such as a deflectionwire, a contraction wire, or puller wire. It is further understood thatthe electrode assemblies 15 and 17 can each be adapted with sensing ringelectrodes, ablation ring electrodes or combinations thereof as desiredor appropriate.

The preceding description has been presented with reference to certainexemplary embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes to the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. Accordingly, the foregoing description should not beread as pertaining only to the precise structures described andillustrated in the accompanying drawings. Rather, it should be read asconsistent with and as support for the following claims which are tohave their fullest and fairest scope.

What is claimed is:
 1. A catheter comprising: an elongated catheter bodygenerally defining a catheter axis; a distal electrode assembly having afirst elongated member defining a longitudinal axis and a plurality ofspines surrounding the member and converging at their proximal anddistal ends, each spine comprising at least one electrode and having acurvature so that the spine bows radially outwardly from the member; aproximal electrode assembly having a second elongated member configuredwith a generally radial portion and a generally circular portiongenerally transverse to the catheter axis, the generally circularportion comprising a plurality of electrodes; a control handle distalthe catheter body; and a tensile member extending between the controlhandle and the distal electrode assembly, wherein the control handle isconfigured for user manipulation of the first tensile member to changethe curvature of the spines.
 2. The catheter of claim 1, wherein theelectrodes on the distal electrode assembly are adapted for sensingelectrical activity in the heart and the electrodes on the proximalelectrode assembly are adapted for ablation.
 3. The catheter of claim 1,wherein the spines have shape-memory.
 4. The catheter of claim 1,wherein the second elongated member of the proximal electrode assemblyhas shape-memory.
 5. The catheter of claim 1, wherein the distalelectrode assembly is adapted to contact an inner circumferentialsurface of a tubular region of the heart and the proximal electrodeassembly is adapted to contact an opening of the tubular region.
 6. Thecatheter of claim 1, wherein the distal electrode assembly is adapted tocontact an inner circumferential surface of a pulmonary vein and theproximal electrode assembly is adapted to contact an ostium of thepulmonary vein.
 7. The catheter of claim 1, wherein the control handlecomprises: a handle body; a core mounted within the handle body, thecore having a longitudinal passage extending therethrough; a pistonhaving a proximal end mounted in the handle body and a distal endextending outside the handle body, the piston being longitudinallymoveable relative to the core and handle body; a first anchor fixedlymounted to the core; a cam receiver mounted within the handle body sothat the cam receiver is longitudinally slidable relative to the pistonand core; a second anchor fixedly mounted to the cam receiver; and agenerally cylindrical cam mounted distal to the cam receiver insurrounding relation to the piston, wherein rotation of the cam relativeto the piston causes longitudinal movement of the cam receiver andsecond anchor, wherein a proximal end of the tensile member is connectedto one of said first and second anchors for user direct or indirectmanipulation of one of the piston and the cam receiver to change thecurvature of the spines.
 8. The catheter of claim 7, wherein the oneanchor is adapted to draw the tensile member proximally to increase thecurvature of the spines.
 9. The catheter of claim 7, further comprising:an intermediate section between the catheter body and the proximalelectrode assembly; and a second tensile member, wherein a proximal endof the second tensile member is connected to the other anchor for usermanipulation of the other anchor for deflecting the intermediatesection.
 10. The catheter of claim 9, wherein a distal end of the secondtensile member is anchored at or near a distal end of the distalelectrode assembly.
 11. The catheter of claim 1, wherein the firstelongated member of the distal electrode assembly is a tube throughwhich a distal portion of the tensile member extends.
 12. The catheterof claim 1, wherein each spine has a non-conductive outer surface onwhich one or more ring electrodes are mounted.
 13. The catheter of claim9, wherein each spine has a support member.
 14. The catheter of claim13, wherein the support member is a nitinol wire.
 15. The catheter ofclaim 1, wherein the distal electrode assembly comprises at least threespines.
 16. The catheter of claim 1, wherein the distal electrodeassembly comprises at least five spines.
 17. The catheter of claim 8,wherein the proximal end of the tensile member is fixedly attached,directly or indirectly, to the first anchor so that longitudinalmovement of the piston relative to the handle housing results inlongitudinal movement of the relative to the catheter body to therebyexpand the distal electrode assembly.